Technical Welding cast...

Clean it-clean-it clean-it....V it out deep......heat it red(not cherry).....weld it with Ni Cad rod.......heat it back up to red(not cherry) wrap it in some type of gl*** cloth insulated blanket and sllooooooowly let it cool.
Worked for me several times.
6sally6
Maybe drill a hole at the end(s) of the crack to stop any further cracking if it does occur after welding.

 

I meant to mention the drilling the ends of the crack with my original post but forgot. Good on you for mentioning it, kind of surprised it wasn't mentioned earlier!

 

Are you sure it's cast iron. Many top mechanisms were made of pot metal.

 

From what I see, there is no end of crack. It is broken in two, but hey, go for it.

 

I would like to add some thoughts here. As a welder with a p***ion for keeping old belongings working, it has been fun playing with many different methods of fixing.

First order of business is to determine the material you are working with. If it is steel, it will throw orange sparks when ground. If it is iron, it will throw red sparks.

Secondly, if you have a way to hold the part securely in the position it needs to stay in, do it so that no stress will be added by trying to get it back into the original position once it has been distorted.

Now you will be able to take the part and clean it thoroughly. The better you are able to remove any impurities, the better your final product will be. Grinding a V from each side should leave you with a center that mates to the other side fairly easily.
(something like this >< )

Once the part is prepared, heat it to about 800 degrees Fahrenheit. Make sure the area is broad because a brittle material like cast iron is very fussy about the heat affected zone next to the weld. Often the break happens right next to the weld if it has not been heat treated sufficiently.

When the metal is very hot, you will be able to braze it, TIG it, oxy-fuel weld it, or stick weld it. Electrodes can be extremely expensive for cast iron, so I hope your part is cast steel. That will be far easier to get a sound weld and cost very little.

My favourite is using the original cast iron rod for oxy-fuel torch welding. It gets dipped in powder flux and makes a messy looking joint, but satisfies the soul in a meaningful way. Just remember to switch sides while welding or brazing to even out the stresses and minimize distortion.

Once the welding or brazing is complete, reheat the same large area to 500 degrees and let that heat cool as slowly as possible. It should take 24 hours to fully cool so don't bother disturbing it until the same time on the next day.

Kitty litter is a very good substance to bury it in. Fire blankets will smoke if you use them. Pink insulation is flammable. Rock wool works if you use enough of it. Ovens also work very well for smaller parts to turn down the heat gradually and accurately over the full 24 hours.

Make sure you have plenty of weld in there. You will be removing the extra, but going over it a second time to fill the missed spots will be agonizing once it has already cooled.

Once it has returned to room temperature you should be able to remove the securing devices that held it like a broken bone in a cast.

If your part was broken like this, it may mean that there is a design flaw and that others may soon follow suit if you locate a replacement.

Best of luck to you with whatever choice you make!


Sent from my iPad using The H.A.M.B. mobile app